LAUSR

Abstract Multiple-route job shop scheduling problem (MRJSP) is an interesting variation of the job shop scheduling problem such that each job has one or more available processing routes, each of which is of a non-identical number of operations. We investigate the bi-objective MRJSP problem to minimize the makespan and the cost of selected processing routes in this work. Different processing routes of any job are of non-equal processing cost. We establish a bi-objective integer programming model, and devise an epsilon constraint algorithm together with a non-dominated sorting genetic algorithm II (NSGA-II). The epsilon constraint method produces exact solutions for small job instances, while NSGA-II can efficiently solve large job instances. Numerical experiments validate the proposed model and algorithms.